Ultra-sensitive biosensor could detect diseases in their earliest stages

By Darren Quick  23:36 May 27, 2012A new ultra-sensitive test developed by scientists from the Imperial College London and Spain's University of Vigo has the potential to detect the earliest stages of a disease, thereby giving any treatment the best possible chance of succeeding. The researchers claim their new biosensor test is capable of detecting biomarkers (molecules which indicate the presence of a disease) at concentration levels much lower than is possible with existing biosensors. While the new test has already proven capable of detecting a biomarker associated with prostate cancer, the team says their biosensor could be easily reconfigured to detect biomarkers related to other diseases or viruses.  The new biosensor consists of nanoscopic-sized gold stars suspended in a solution containing blood-derived proteins. Antibodies, which latch onto a biomarker when it is detected in a sample, are attached to the surface of the nanostars. In their study, the researchers used an antibody that latches onto Prostate Specific Antigen (PSA), a biomarker associated with prostate cancer. A secondary antibody, which has an enzyme called glucose oxidase attached to it, creates a distinctive silver crystal coating on the gold stars that can be detected through an optical microscope, thus signaling that PSA is present.  The researchers were able to detect PSA at 0.000000000000000001 grams per milliliter, which is comparable to the most sensitive biosensor tests currently available and significantly more sensitive than an existing Enzyme-linked Immunosorbent Assay (ELISA) test that can detect PSA at 0.000000001 grams per milliliter.  "Using current technology to look for early signs of disease can be like finding the proverbial needle in a haystack," said Professor Molly Stevens from the Departments of Materials and Bioengineering at Imperial College London. "Our new test can actually find that needle. We only looked at the biomarker for one disease in this study, but we're confident that the test can be adapted to identify many other diseases at an early stage."  The researchers next plan to conduct further clinical testing to examine the potential of the new biomarker in detecting different biomarkers associated with HIV and other infections.  The team's research was appears in the journal Nature Materials.